Early observations of switchbacks by Parker Solar Probe (PSP) provided a stark demonstration
of the dynamic nature of the near-Sun solar wind [1]}.
These strong and sudden reversals of the background magnetic field, which
are known from electron measurements to have the topology of local folds in field lines (as opposed to global polarity reversals [2]}),
contain significant energy content compared to the background plasma. This suggests they play a
role in — or are least a helpful diagnostic of — the key processes that heat and
accelerate the solar wind [3]}. As such, a range of different explanations have been
put forth for their origin, each relating in some way to fundamental low-coronal or solar-wind physics with
the switchbacks emerging as an observable consequence. These explanations include models relating
to interchange reconnection near the solar surface [4]}, [5]}, [6]}, [7]}, low-coronal jets or other motions [8]}, [9]},
field-line folding due to asymmetries from interchange reconnection [10]}, instabilities between different
wind streams [11]}, or the growth of Alfvénic fluctuations due to plasma expansion [12]}, [13]}, [14]}.
Given these widely differing ideas, each of which provide different
predictions for switchback properties and occurrence rate, a clear path forward to bettering our understanding of the solar wind
presents itself: quantify various (hopefully) unique and observationally testable predictions for each model, then
compare these to observations.
